Background

 

Cowpea (Vigna unguiculata) is an important source of nutritional and food security for many households in Zambia. Plant architecture of cowpea plays a major role in its adaptation to pest resistance and easy harvesting. For example, cowpea plants with long peduncle and erect pods have previously been associated with resistance to Pod Borer (Marica vitrata) while number of pods per peduncle is an important component of seed yield. Creating genetic variation for this yield component and understanding the genetic basis of that variation could support genetic enhancement of seed yield in cowpea.

 

A cowpea mutant germplasm known as Mutant Diversity Panel (MDP), comprised of 750 M5 mutants, exhibits diversity for a wide range of traits including those for plant architecture. MDP is also variable for yield component such as number of pods per peduncle. An understanding of the genetic basis of the plant architecture could support development of cowpea germplasm that is less susceptible to pest damage, easier to harvest and higher yielding. The MDP will be evaluated for peduncle length, pod orientation and number of pods per peduncle in multi-locational field trials to identify mutants with all the three traits or with two of the three mentioned traits.

 

When a mutant/line with a combination of the three traits or at least two of the mentioned traits is identified/or developed, it will be crossed with unrelated Zambian varieties. The F1 that will be developed will be selfed to F2 and then use single seed descent method to advance the F2’s to F4:5 families. The F4:5 population will then be phenotyped in multi locational field trials for peduncle length, pod orientation and number of pods per peduncle. The F4:5 RILs will also be genotyped with a SNP Chip. Thereafter QTL analysis will be conducted to identify QTL for peduncle length, pod orientation and number of pods per peduncle.

 

The project will develop and release cowpea varieties that have a plant architecture that supports easy harvesting of cowpea, and potentially reduced Maruca infestation and higher productivity. The mutant germplasm used here will be made available to other interested KT-funded cowpea projects as genetic resource for identification of valuable traits to support breeding objectives in their respective countries.