Rich Pratt Professor and Head, Plant and Environmental Sciences

Transcription

1 Rich Pratt Professor and Head, Plant and Environmental Sciences 1

2 Diversity of Arido-American Land Races of Maize B.S. - U of A 1976 M.S. - U of A 1978 Ph.D. - Purdue University 1985 Interspecific hybridization of Phaseolus Professor Ohio State University Corn breeding Special research assignment with NSS 2

3 What type of corn will we need in the future? What are/will be the big issues? Food Security - Human health and nutrition? Agriculture in harmony with the environment? Impact of climate change? Increasing genetic vulnerability? 3

4 Arido-America = a broad, dry climatic region in the southwestern USA and northern Mexico Wikipedia.org Why work with diverse germplasm.from this area? 4

5 Lots of native corn still remains in Aridoamerica for how long? Unrealized potential: It is a useful germplasm source for: Development of regional, sustainable, diversified agriculture Trait improvement in other types of corn highly pigmented kernels, enhanced protein quality in many floury types? (health and nutrition) may be useful for stress tolerance (global warming) 5

6 Roughly 2000 accessions (all species) at NS/SEARCH Maize Collection Tohono O'odham 60-day Yoeme Blue Navajo Red Hispanic Pueblo Red Hernandez Multi-Color Flor del Rio Hopi Hominy Zea Mix Navajo Red San Felipe White Onaveno. 6

7 Representing Colorado Plateau NE Arizona (Four Corners area) Navajo Nation [Hopi Nation] A few Sonoran Desert Besthike.com Tohono O-odham NW Mexico (Copper Canyon) Tarahumara Rei.co m 7

8 NS/SEARCH Conservation Farm near Patagonia, Arizona mid-altitude 8

9 Open-pollinated Land Race Single-Cross Hybrid Corn Belt Dent (B73/Mo17) 9

10 Materials - 50 entries- 48 Native Seeds collection - 2 entries were checks (B73/Mo17 and OhS12) - At two locations (AZ and OH) across two seasons

11 Diversity! Flor del Rio Plateau 12-Row SW and Hopi 11

12 Onaveno 12

13 Results 13

14 14

15 15

16 Waller-Duncan grouping by kernel color (cont.) Color N Carotenoid range Color N Anthocyanin range orange a blue a yellow a purple ab mix b mix bc purple bc red bc brown bc r(str) c pink bcd brown c blue bcd pink c red bcd orange c white cd yellow c r(str) d white c

17 2009 Plan: Anthocyanin Selection high anthocyanin landraces from NSS - 6 lines containing mg/100g Cross pollination - 6 NSS lines x Ohio Blue (Ned s Blue/Blue Clarage) - Reciprocal cross Objectives - To introduce high anthocyanin from NSS into Ohio Blue - To see the heterotic relationship between two populations 17

18 Acknowledgements! OSU-OARDC SEEDS Program co-investigator Joe Scheerens Native Seeds/SEARCH collaborator Suzanne Nelson Si Hwan Ryu Mark Casey Lindsay Werth Benito Gutierrez Chris Lowen Andrew Burt 18

19 Corn breeding.. GEMS 0002 parent line Fusarium ear rot susceptible Selection Works!

20 Breeding cross-pollinated crops Breeders seek to increase the frequency of desirable alleles in a population (also need to maintain genetic diversity in the population allows further improvement) Population improvement -- intra-population -- e.g. in a maize open pollinated population (recurrent mass selection for multiple cycles) -- interpopulation reciprocal recurrent selection, evaluate crosses between populations, exploits inerpopulation heterosis Unit of selection may be plants or lines (e.g. selfed, fullsib (sibling) crosses) 20

21 OPPs Many OPPs in wind-pollinated species have been replaced with hybrids conduct inbred line development then make hybrids with inbred parents e.g. maize 21

22 OPPs Essentially all maize opps were replaced by hybrids in the U.S. by the early 1950s Still important where farmers save seed 22

23 OPPs Recurrent selection heterozygous and heterogeneous, improve a general population e.g. Cash RS ( Cash was good local corn a farmer variety in SW Ohio) Synthetic cultivars heterozygous and heterogeneous, produced by planned matings of selected genotypes -- can be many but often e.g Breeding population pull parents from a synthetic population or breeding population Tend to have a broad genetic base Composite is a mixture of genotypes maintained in a bulk often a balanced composite (equal no. of seed) 23

24 Controlled pollinations are an important part of maize breeding programs Self-pollination must be controlled Self-pollination results in inbreeding depression Self-fertilization reveals desirable gene combinations as well as undesirable recessive alleles 24

25 Linearity of inbreeding depression with F 1 Height Inbreeding depression in Maize Mean Inbred Outbred.6 Yield F 25

26 Pollination and its control: An example of a monecious species: maize CORN POLLINATION BIOLOGY (Wikipedia.com) 26

27 Maize Pollen The pollen grain is the male gametophyte About 25 million grains per plant are produced in the anthers Maize pollen is large (90 to 100 microns dia.) and heavy (.25 µg!) Viable for 2 to 4 hours, longer under favorable conditions 27

28 Pollination Monoecy (male and female floral parts on same plant) Anthers dehisce - windborne pollen Pollen lands on silks, (stigmatic surface), germinate and pollen tubes reach egg cells Pollen effects fertilization of the egg to give rise to embryo 28

29 A silk with stained grains of pollen A well developed ear shoot should have 750 to 1,000 ovules each producing a silk Silks are covered with fine, sticky hairs which serve to catch and anchor pollen grains Average of approx. 12 pollen grains per silk observed (poss. 5-6k) 29

30 Distance Traveled? Most pollen falls within about 5-6 meters (Hutchcroft, 1958) Pollen can travel 20 miles on a strong wind current? (hearsay) Most of the pollen cloud produced by a plant misses the parent plant (5 to 10% hits ) It all depends on the wind and the weather 30

31 Corn breeding swapping bags Glassine ear shoot bag silks emerge but are protected Tassel bag pollen is shed but it is contained in the bag 31

32 Corn pollination Effective pollination is necessary for normal yield (pollen and silk are heat and stress susceptible) Effective pollination control is necessary for hybrid seed production Pollination source can influence grain appearance (pigmentation) and chemical compositional values (e.g. oil) xenia effect Pollen dispersal may result in GMO corn traits winding up where they are not wanted Controlled pollinations are an important part of breeding programs 32

33 Isolation Requirements (AOSCA Study 2001) Seed producer s point of view pure seed production (95-98% purity) Distance from nearby fields, border rows, empirically derived over time e.g. 290 ft. + 6 border rows for field <20A New era GMO detection Hybrid grain production fields were an issue e.g. Star-link maize 33

34 Effects of stress on pollination Pollen becomes sterile at high temperatures (e.g. in excess of 95 degrees F) especially when accompanied by low relative humidity (the outer membrane of a pollen grain is very thin) Silk growth slows down and it may even stop entirely (or does it dessicate?) Asynchrony of flowering results -- increasing the anther-silk interval (ASI) What are the implications in nature, breeding, hybrid production? 34

35 Types of selection Mass selection the easiest and most inexpensive; select based on phenotype to improve average performance of population General clean up keeping a variety true to type Directed breeding from a base population 35

36 Synthetics cultivars/improved populations Synthetics can be improved for production (cultivars) and they may also be produced for use as a breeding resource or base population Synthesizing a population by combining many parents e.g. BSSS comprised of 20+ maize inbreds 36

37 Iowa Stiff Stalk Synthetic (BSSS) Elite inbred lines can be derived from the population for production of hybrids >> cycles of recurrent selection >> produced inbreds B14, B37, B73, B84 suitable for use as parents in hybrids 37

38 End products An improved population or synthetic cultivar Elite inbred lines can be derived from the improved population for production of hybrids Developing mixed genotype cultivars (but uniform for phenotypic traits of the cultivar) 38

39 Types of recurrent selection 1) Phenotypic recurrent selection mass, family 2) Recurrent selection for GCA (broad based tester) 3) Recurrent selection for SCA (inbred tester) 4) Reciprocal recurrent selection 39

40 Advantages and disadvantages of different recurrent selection schemes Mass selection Advantages: relatively easy and inexpensive Disadvantages: mass selection does not work so well for quantitative traits, no pollen control (no idea what the worth of male parent plants is) Save selected seed and replant the following season.completes one cycle 40

41 Family selection methods 1) Creation of a family structure (e.g. S, FS, HS) 2) Evaluation of families and selection of superior ones advantage can be replicated, save remnant seed 3) Recombination of selected families (intermating) plant remnant seed of superior families during next season 41

42 Reciprocal recurrent selection Pops A and B Pollen from one plant X several plants from the other population e.g. A1 pollen X B-a, B-b, B-c, B-d average A1 X (B-abcd) Determines GCA of the population with multiple lines, given SCA match of two parents can give rise to new hybrids? 42

43 Reciprocal recurrent selection Plants from one population are testers for plants of another population; can also self the lines and use them for making next cycle Cycles should build up combining ability for the other population..establish or reinforces heterotic patterns 43

44 Optimizing gain through selection in population improvement Genetic variance, start with it and try to keep it Selection intensity limit to the best performers Generations per cycle, how rapidly can a cycle be completed? Field plot technique 44

45 HYBs Hybrids (HYB) - heterozygous, homogeneous Single cross.two uniform inbred parents (homozygous and homogeneous) Make new hybrid from parents with best specific combing ability (SCA combinations) 45

46 Use of testers Selection of SCA and GCA permits selection for genetic variance other than additive variance - e.g. dominance, overdominance etc. Increasing selection intensity increases response to selection unless it results in genetic drift or loss of desirable genetic variation 46

47 Implications of HYB The cultivars are more productive (and easier to manage) but they are more vulnerable. Enhanced uniformity brings with it associated problems such as increased vulnerability e.g. to disease. 47

48 Current Breeding Effort An estimated 85% of the corn grown in the US today is genetically modified, and most seed companies continue to phase out non-gmo corn seed varieties. Thirty-two percent of conventional farmers wish their seed company offered more non-gmo options, according to a 2010 survey. Where are improved non-gmo corn hybrids available? Can farmers obtain them to plant on their farms? 48

49 A different model: UNTN US Testing Network: Cooperators launched the US Testing Network in 2009 to rebuild the dwindling selection of non-gmo corn seed. PFI acts to coordinate and as the fiscal agent today. The US Testing Network (USTN) is a group of independent seed companies, public corn breeders and private corn breeders who work to test non-gmo corn hybrids across the US. The goal is to improve the quality and quantity of non- GMO corn hybrids available in the marketplace. 49

50 Develop new non-gmo corn hybrids Some of the companies involved in the network include Albert Lea Seed House, American Organic Seed, Blue River Hybrids, Brownseed Genetics, Doeblers Hybrids*, and Organic Valley. University members include Cornell, and Ohio/New Mexico State. The Michael Fields Institute is involved, as are public corn breeders from the USDA s Agricultural Research Service at Iowa State University. 50

51 Growing network USTN members tested corn at 36 locations stretching from New England south to North Carolina, west to Ohio, Illinois, Wisconsin, Iowa, Minnesota, and North Dakota and New Mexico. USTN is analyzing data from the tests, which will lead to the development of new corn hybrids for both conventional, non-gmo and organic production. 51

52 NIFA OREI Grant just started Strengthening Public Corn Breeding to Ensure that Organic Farmers have Access to Elite Cultivars: Breeding for the Eastern and Southwest USA Agreement No. Cooperator: New Mexico State University Objective: 1) Contribute populations to and provide testing sites/evaluations for a joint experiment to catalog germplasm for organic production, 2) cooperate in an inter-regional breeding effort concentrating on the eastern Corn Belt and Southwestern USA, 3) take the lead in breeding/evaluation for biotic and abiotic stresses and enhanced grain quality 4) participate in USTN trials and pre-trials and 5) cooperate in onfarm evaluations and stress nurseries. 52

53 Tempis fugit Time flies like an arrow; fruit flies like a banana." Groucho Marx 53