Genetic control of duration of pre-anthesis phases in wheat (Triticum aestivum L) and associated traits: leaf number and phyllochron

GONZÁLEZ, FERNANDA G; TERRILE IGNACIO; VANZETTI, LEONARDO; BÖRNER, ANDREAS; PLIESKE, JÖRG; GANAL, MARTIN; RÖDER, MARION

Conferencia; First Latinamerican Conference on Plant Phenotyping and Phenomics for Plants breeding; 2015

Wheat (Triticumaestivum L) production is critical for human diet. It has been predictedthat an increase by ca.50% from current volumes is necessary to fulfil the projected growth of wheat demand.As the cropped land will hardly increase, production should rise mainly via higheron-farm yields which are closely linked to cultivar´s potential yield. Time to anthesisis the main trait defining adaptation to the environment and thereby the yield potentialof cultivars (i.e. the maximum yield without water,nutrient or biotic restrictions). The fine-tuning of the relative duration ofpre-anthesis phases could modify the yield potential of cultivars alreadyadapted to the environment. If the period of spike growth is increased withoutchanging the anthesis date (via longer duration of the pre-anthesisreproductive phase from first node to anthesis, 1N-AN, and a reduction ofprevious phases from emergence to first node, E-1N), the number of fertileflorets and grains would increase (being associated with higher spike growth)and thus raising the yield potential. To fine-tune wheat development up to anthesis, the environmental andgenetic basis that control the vegetative and reproductive pre-anthesis phasesshould be known. Two double haploid populations with a common parent derivedfrom the cross of French x CIMMyT elite germplasm (Baguette 19 x BioINTA 2002and Baguette 11 x BioINTA 2002) were genotyped with the 90K SNPS Infinium arrayand sown during two years under field conditions in a temperate area with mildwinters (Region II of the Argentine production area at 33º 51? S, 60º 56? W). Theduration of the following pre-anthesis phases were determined: (i) fromemergence to first detectable node (E-1N: leaf + spikelet differentiation phases), (ii)from first detectable node to flag leaf appearance (1N-FL) and (iii) from thento anthesis (FL-AN), where most florets develop and die. The number of leavesemerging from main stems (LN) and the rate of appearance (phyllochron) in eachsub-phase were also measured. The E-AN phase ranged from ca 1,300 to 1,800ºcdfor B19 x B2002 while it varied from ca. 1,300 to 1,600 for B11 x B2002. Theduration of pre-anthesis sub-phases also showed variation within each population,ranging from 20 to 46% for E-1N and from 2 to 3 fold for 1N-FL and FL-AN. TheLN appeared during E-1N ranged from ca. 8.2 to 11.5 while the LN appeared during1N-FL phase varied from ca. 1.1 to 3.9. The phyllochron of the first leaves (E-1N)ranged from ca. 86 to 111 ºCd/leaf, while the one of the later leaves (1N ?FL)varied from 60 to 258 ºCd/leaf (considering both populations). The phyllochronshowed moderate to low narrow sense heritability. Based on the marker analysisand map information of the SNP markers, two main QTLs were detected in both populationsaffecting most of the evaluated traits. The first QTL mapped on chromosome 5Awith the peak marker being in the Vrn-A1 gene and the second QTL was onthe 5B chromosome with the peak marker in the Vrn-B1 gene. The two genessignificantly affected the pre-flowering E-1N and 1N-FL sub-phases andsignificant epistatic interactions between them were detected. Winter allelesin Vrn-A1 and Vrn-B1 genes increased the duration of the E-1Nphase sub-phase but reduced the duration of the following 1N-FL sub-phase. Inthe case of FL-AN, only the Vrn-B1 showed a significant effect with thewinter allele increasing the duration of the sub-phase. Additionally both genesaffected the LN in the E-1N sub-phase, and only Vrn-A1 affected the LNin the 1N-FL sub-phase. Winter alleles produced an increment in the final LN inthe affected sub-phases. Finally, no relevant effect was detected onphyllochron of leaves. These results will help to manipulate wheat developmentto anthesis to improve yield potential.