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ARS Home » Plains Area » Las Cruces, New Mexico » Cotton Ginning Research » Research » Publications at this Location » Publication #309217
Title: Transgressive segregation in an Acala × Acala Hybrid for the development of glandless cotton germplasm

Author
item ZHANG, JINFA - New Mexico State University
item FLYNN, ROBERT - New Mexico State University
item IDOWU, OMOLOLU - New Mexico State University
item WEDEGAERTNER, TOM - Cotton, Inc
item Hughs, Sidney

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2016
Publication Date: 6/30/2016
Citation: Zhang, J.F., Flynn, R., Idowu, O.J., Wedegaertner, T., Hughs, S.E. 2016. Transgressive segregation in an Acala × Acala Hybrid for the development of glandless cotton germplasm. Journal of Cotton Science. 20:145-153.

Interpretive Summary: All cotton being commercially grown in the U.S., both upland and Pima, contain a substance called gossypol in glands located throughout the plant structure including its seeds. Gossypol is a natural toxin that serves as a natural insecticide. Cottonseed is very high in protein but gossypol’s presence in glands within the seed limits its usefulness as a protein source to primarily dairy cattle and other ruminants. In the past, there have been upland cotton varieties developed that did not contain gossypol in the seed (glandless) but these varieties were more vulnerable to insect damage resulting in lower fiber yields and were not commercially successful. With the elimination of some of the more damaging cotton insect pests in the US cotton belt it might be possible to grow glandless cotton without loss of fiber yield due to insect pressure. Due to its amount and quality of its protein, glandless cottonseed could be an important direct source of protein for both commercial fish farms and for humans and significantly increase the market value of the cottonseed. However, the existing glandless cotton lines have significantly lower fiber yields than current commercial cotton varieties. These lower yields make the glandless varieties economically not viable. This research was conducted to determine if glandless varieties could be crossed through several generations of classical breeding with glanded cotton varieties and augment both fiber yield and maintain fiber quality and glandless characteristics in the offspring. Overall results were mixed with more negative results in retaining fiber quality and increasing the fiber yield of glandless germplasm than positive results. More work remains to be done to produce a commercially competitive glandless cotton variety.

Technical Abstract: There exists a 10-20% yield gap between the best high-yielding glandless cotton and current commercial cultivars. Improvement in lint yield is vital to commercial production of glandless cottons. The objective of this study was to address if the current glanded Acala 1517-08 cotton can be converted to glandless cotton without a yield penalty by crossing it with an obsolete glandless Acala GLS through a repeated pedigree selection. From ca. 500 F2 plants, 18 glandless individuals were selected based on a visual field performance and their F4 lines were compared with both parents. This led to a selection of 77 F6 lines for a further replicated field testing. The field results from both F4 and F6 lines allowed addressing if transgressive segregation occurred that can be utilized in breeding. Among the 18 F4 lines, eight had higher lint yield (LY) than the higher parent Acala 1517-08 by more than 10% due to unexpected lower yield of the parent. Five F6 lines yielded 90-96% lint of Acala 1517-08, three of which were selections from two of the eight high-yielding F4 lines, but none had greater LY than the higher parent due to the fact that none had higher lint percentage (LP) or boll weight (BW) than the higher parent. Three F6 lines had significantly lower LY than the lower parent Acala GLS. Transgressive segregation in the negative direction was also observed in that four and 22 F6 lines had significantly lower BW and LP than the lower parent, respectively. In F4 and F6, 9 and four lines had significantly lower fiber length (UHM) than the lower parent Acala 1517-08, respectively, while five F6 lines had longer UHM than the higher parent Acala GLS. Two F4 and 10 F6 lines had weaker fibers than the lower parent Acala 1517-08, but none had stronger fibers than Acala GLS. All the F4 and most F6 lines had micronaire (MIC) between the two parents except for one with coarser fibers than the higher parent and five with lower MIC than the lower parent Acala GLS. In conclusion, five lines produced 90-96% LY of Acala 1517-08 with Acala premium fiber quality and should be tested in more environments. Positive transgressive segregation for LY, LP and BW should not be expected in Acala × Acala crosses, while negative transgressive segregations occurred frequently for the three traits and fiber strength. For UHM and MIC, negative transgressive segregations occurred more frequently than positive ones. Overall, there was no transgressive segregation for fiber uniformity, elongation and short fiber content.