Chapter 5 Genetic Analysis of Apomixis - cimmyt

F..ding Itl. World in the 211t c.n'ury: PI.., 8r.....g. 8io,.o.oIogy, and tile Po,••tlal Role of ApamiJlil 7even more double and triple annual croppingcycles and more extensive use of yieldenhancingtechnologies such as hybrid seed,by the overwhelming majority of farmers,including those with limited purchasingpower. Hybrid seed's potential to increaseproduction has been demonstrated by hybridrice in China. From 1980 to 1990, Chinaincreased its rice production by roughly 32.5million tons, or 22 percent, while decreasingthe area planted to rice by roughly 2.2 millionhectares, or six percent (FAO 1990). Yuan Longping,the "father of hybrid rice" in China,speculates that full exploitation of the heterosisavailable in rice could provide another 3D-50percent increase in yield (Yuan 1993). Newhybrid lines that are suitable for other regionsof Asia are slowly becoming available.Biotechnological tools (such as geneticallyengineered male sterility systems for elitebreeding lines) and the use of molecularmarkers to select parental lines that combinehigh levels of heterosis with other desirablecharacteristics can accelerate this process andmake the use of hybrid rice technology morebroadly applicable. And, as reported later inthis book, progress is being made on usingapomixis as the ultimate tool for fixingheterosis in cereals, thereby making thebenefits of hybrid seed available to farmers atminimal cost.African and Latin American farmers could alsobenefit from hybrid seed that self-replicatestlvough apomixis, although the application ofapomixis to niche breeding could yield evenmore consequential results. If apomixis can beintroduced into staple food crops, cultivarsthat perform well under local conditions couldbe genetically fixed early in the selection cycle.Under this scheme, variability would begenerated through traditional hybridizationor any other technique noted in theevolu tionary phase (see Figure 1.1). Theresul ting population of plants would begrown and evaluated under local conditions,and the plants that performed best could beselected and quickly developed intogenetically stable superior cultivars byincorporating the gene(s) for apomixis. Forcrops that are normally reproduced fromtubers or vegetative cuttings, apomixis wouldenable the multiplication and disseminationof improved varieties as true seed.In short, apomixis has the potential to makea significant contribution toward meetingfood production demand throughout thedeveloping world in the 21 sl century. Becauseof its limited profit potential, this technologywill probably not be fully developed in theprivate sector. Therefore, if the full potentialof apomixis as a breeding tool to help the pooris to be realized, the necessary research anddevelopment must be undertaken by thepublic sector international agriculturalresearch system-and the results mustremain freely available to public sector cropbreeding programs.ReferencesBongoorts, J. 1994. Population policy options in the developing world.Science 263: 771-76.FAD. 1990. Selected Indicators of Food and Agriwhure Development inth~ Asian·Pacific Region. Rome: RAPA Publications.FAD. 1992. The State of Food and Agriculture. Rome: FAD.FADSTAT. 1998. Populolian Statistics. Rome: FAD.luts, W, W. Sanderson, and S. Scherbov. 1997. Doubling of worldpopulation unlike~. Holure 387: 803-05.United Nations. 1997. World Population Prospeds: The 1996 Revision.New York: United Nations Population Division.Yuan, L.p. 1993. Progress of two-line system in hybrid rice breeding. InK. Muralidhoran and E.A. Siddig (eds.), Hew Frontiers in RiceResearch. Hyderabad, India: Directorate of Rice Research. Pp. 81r­93.