YIIFSWA-II participates in Plant and Animal Genome Conference (PAG XXVIII) in San Diego

Billed as the largest Plant and Animal Genome meeting in the world, scientists from around the world converged at San Diego, California, USA, for PAG XXVIII from 11 to 15 January to promote research discoveries, exchange ideas, and gain new insights on plant and animal genome research and development.

YIIFSWA-II scientists, Norbert Maroya and Morufat Balogun, participated in the conference and made presentations on “The effect of vine position of Aeroponics mother plant on the performance of seed yam production” and “Genetic fidelity of yam planting materials produced with novel high ratio propagation technologies based on morphological, ploidy and SSR markers” respectively, at the Yam Genomics workshop. Many other colleagues from IITA attended the meeting and made presentations.

In his presentation, YIIFSWA-II Project Leader and Principal Scientist of the yam Aeroponic System (AS), Maroya, indicated that cutting vines from different parts of the plant can affect both the survival and tuber yield from the single-node vine seedlings. After three consecutive years of cropping and tuber harvest under irrigation, the scientist observed a wide variance in the survival of seedlings and the size of tubers generated. Therefore, research was conducted to investigate the factors contributing to the variation.

When describing the methodology and results of the study, he stated that non-endophytic, clean plantlets from the Temporary Immersion Bioreactor System (TIBS) of two out of the three white yam varieties promoted by the project, Kpamyo and Asiedu were planted in the AS and left to grow for four months. After this, single node vines were cut from the top, middle, and bottom portions of the plant and planted in nurseries. After five weeks, he noted a significant difference in the survival and production of new shoots between the varieties and among the three types of vines. The survival rate of the single-node vines cut from the top, middle and bottom parts of the plant for the Asiedu variety was 94%, 55%, and 64%, respectively, and for the Kpamyo variety, it was 84%, 74%, and 70%, respectively.

Planted under rainfed conditions in the field, Maroya also noted significant variations among the three sources of seedlings. He said, “The varieties and the vines had substantial differences in the number of plants at harvest and sizes of tuber produced after six months in the field. The yields (t/ha) from vines from the top, middle, and bottom for Asiedu was 7.95 t/ha, 1.05 t/ha, and 2.54 t/ha, respectively and for Kpamyo it was 6.04 t/ha, 2.95 t/ha and 4.56 t/ha, respectively.”

He concluded that the result of the study demonstrates that vines from the top are more productive than the vines from the bottom and middle. Therefore, the specific need regarding tuber size should determine the position of vine cuts. However, there are fewer big size tubers under rainfed than on irrigation cropping.

In her presentation, Balogun, YIIFSWA-II Tissue culture specialist, indicated that the study was done to investigate and validate the genetic integrity of planting materials produced through High Ratio Propagation Technologies (HRPTs). “During the initial years of YIIFSWA-II, concerns were raised on genetic variance or deviation of plantlets propagated through a combination of HRPTs. Therefore, the study was conducted to verify if using HRPTs causes a genetic variation in the plant,” she said.

For the methodology, she indicated that the planting materials of four varieties of white yam were compared with their mother plants that were propagated with conventional methods. The varieties included two released improved varieties, Kpamyo (TDr 95/19177) and Asiedu (TDr 89/02665), as well as two popular registered landraces, Pepa and Amula propagated using HRPTs (Conventional tissue culture, Temporary Immersion Bioreactor System (TIBS), AS, and Vine cutting technologies in seven different combinations). The samples were subjected to visual morphological assessment, ploidy level, and eight Simple Sequence Repeat (SSR) marker delineation. The test was done using twelve morphological descriptors, flow cytometry, and molecular techniques respectively. Balogun stated that the result showed that “twining direction, presence of hair, leaf margin, had 100% similarity within the population while other characters had 90% similarity. Flow cytometry did not show a significant variation of 2C DNA content among treatments as well as with their mother plant.

The number of alleles varied from 2 to 6 with an average of 4 per locus. The highest and lowest number was found with primer YM8 and YM69, respectively. Major Alleles Frequency (MAF) varied from 0.54 (YM69) to 0.79 (YM27) with an average of 0.63. Low genetic diversity was observed in the population analyzed due to the 0.51 value obtained for the heterozygosity. The polymorphic information content PIC ranged from 0.29 (YM27) to 0.56 (YM18) with an average of 0.45. The dendrogram generated by six informative out of the eight SSR markers used showed that the clones and their mother plants clustered together. Based on these findings, there is no genetic variation produced as a result of any of these high ratio propagation technologies.

The yam genomic workshop was set up to promote recent advancements in the development of genomic resources and related tools for yam to accelerate genome assisted improvement.