Study on early inflorescence development in bread wheat (T. aestivum L.) lines with non-standard SCR-morphotype

Features of wheat (Triticum aestivum L.) inflorescence development define its architecture and have an impact on yield potential. Wheat lines and forms with altered inflorescence morphology are important genetic resources for the study on the genetic mechanisms underlying plant developmental programs and inflorescence architecture; they are also important for practical use to increase productivity. Normally, wheat spikelets are arranged in two parallel rows along the spike axis. The SCR (screwed spike rachis) lines represent a non-standard morphotype, which is characterized by a spiral arrangement of spikelets along the spiked rachis. The study of the early stages of the inflorescence development in SCR-lines using light and scanning electron microscopy revealed that the spiral arrangement of spikelets were not related to changes at the early stage of inflorescence development, and resulted from spiral growth of spike rachis cells at later stages of spike growth. Thus, the spiral arrangement of spikelets in cereal inflorescence may have resulted not only from peculiarities of the mutual arrangement of spikelet meristems (phyllotaxis), but also from cell growth features at later stages of inflorescence growth. It was shown that SCR is inherited as a dominant monogenic trait; its expression can be modified by genotypic background. The SCR-lines characterized using light and scanning electron microscopy represent an important genetic resource for further study of the molecular-genetic mechanisms determining plant architecture. Furthermore, they can be used to develop wheat lines and cultivars with new inflorescence phenotypes.

bread wheat, Triticum aestivum L., inflorescence development, phyllotaxis, scanning electron microscopy

1. Babb S., Muehlbauer G.J. Genetic and morphological characterization of the barley uniculm2 (cul2) mutant. Theor. Appl. Genet. 2003;106: 846-857. DOI 10.1007/s00122-002-1104-0.

2. Bartlett M.E., Thompson B. Meristem identity and phyllotaxis in inflorescence development. Front. Plant Sci. 2014;5:508. DOI 10.3389/fpls.2014.00508.

3. Boden S.A., Cavanagh C., Cullis B.R., Ramm K., Greenwood J., Finnegan J.E. Trevaskis B., Swain S.M. Ppd-1 is a key regulator of inflorescence architecture and paired spikelet development in wheat. Nat. Plants. 2015;26(1):14016. DOI 10.1038/nplants.2014.16.

4. Bonnett O.T. The development of the wheat spike. J. Agric. Res. 1936; 53:445-451.

5. Dobrovol’skaia O.B., Badaeva E.D., Adonina I.G., Popova O.M., Krasnikov A.A., Laĭkova L.I. Investigation of morphogenesis of inflorescence and determination of the nature of inheritance of “supernumerary spikelets” trait of bread wheat (Triticum aestivum L.) mutant line. Ontogenez = Ontogenesis (Moscow). 2014a;45(6):434-441. PMID:25739301 (in Russian)

6. Dobrovol’skaya O.B., Martinek P., Adonina I.G., Badaeva E.D., Orlov Yu.L., Salina E.A., Laikova L.I. Effect of rearrangements of homoeologous group 2 chromosomes of bread wheat on spike morphology. Vavilovskii Zhurnal Genetiki i Selektsii = Vavilov Journal of Genetics and Breeding. 2014b;18(4/1):672-680 (in Russian)

7. Dobrovolskaya O., Martinek P., Voylokov A.V., Korzun V., Röder M.S., Börner A. Microsatellite mapping of genes that determine supernumerary spikelets in wheat (T. aestivum) and rye (S. cereale). Theor. Appl. Genet. 2009;119:867-874. DOI 10.1007/s00122-0091095-1.

8. Dobrovolskaya O., Pont C., Sibout R., Martinek P., Badaeva E., Murat F., Chosson A., Watanabe N., Prat E., Gautier N., Gautier V., Poncet Ch., Orlov Yu., Krasnikov A.A., Bergès H., Salina E., Laikova L., Salse J. FRIZZY PANICLE drives supernumerary spikelets in bread wheat (T. aestivum L.). Plant Physiol. 2015;167:189-199. DOI 10.1104/pp.114.250043.

9. Dorofeev V.F., Korovina O.N. (Eds). Kulturnaya flora SSSR [Cultivated flora of the USSR]. T. 1. Pshenitsa [V. 1. Wheat]. Leningrad, Kolos Publ., 1979. (in Russian)

10. Ikeda K., Nagasawa N., Nagato Y. Aberrant panicle organization 1 temporally regulates meristem identity in rice. Dev. Biol. 2005;282:349-360. DOI 10.1016/j.ydbio.2005.03.016.

11. Kellogg E.A., Camara P.E., Rudall P.J., Ladd P., Malcomber S.T., Whipple C.J., Doust N.A. Early inflorescence development in the grasses (Poaceae). Front. Plant Sci. 2013;4:250. DOI 10.3389/fpls.2013.00250.

12. Laudencia-Chingcuanco D., Hake S. The indeterminate floralapex1 gene regulates meristem determinacy and identity in the maize inflorescence. Development. 2002;129:2629-2638.

13. Malcomber S.T., Preston J.C., Reinheimer R., Kossuth J., Kellogg E.A. Developmental gene evolution and the origin of grass inflorescence diversity. Eds. P.S. Soltis, J. Leebens-Mack. Developmental Genetics of the Flower, 2006. Advances in Botanical Research. 2006;44:423479. http://dx.doi.org/10.1016/S0065-2296(06)44011-8.

14. Martinek P., Bednar J. Gene resources with non-standard spike morphology in wheat. Proc. Int. 9th Wheat Genet. Symp., Saskatoon, Canada. 2–7 Aug. 1998. Ed. A. Slinkard. Univ. Saskatchewan. Saskatoon, 1998;286-288.

15. Martinek P., Bednar J. Changes of spike morphology (multirow spike – MRS, long glumes –LG) in wheat (Triticum aestivum L.) and their importance for breeding. Proc. Int. Conf. “Genetic Collections, Isogenic and Alloplasmic Lines”. Novosibirsk, 2001;192-194.

16. Rokitsky P.F. Biologicheskaya statistika [Biological statistics]. Minsk: Vysshaya Shkola Publ., 1973. (in Russian)

17. Shitsukawa N., Kinjo H., Takumi S., Murai К. Heterochronic development of the floret meristem determines grain number per spikelet in diploid, tetraploid and hexaploid wheats. Ann. Bot. 2009;104:243251. DOI 10.1093/aob/mcp129.

18. Smoček J. Screwedness of the spike rachis – A new phenomenon in wheat spike morphology. Rostlinná Vỳroba. 1991;37:507-514.

19. Thompson B.E., Bartling L., Whipple C., Hall D.H., Sakai H., Schmidt R., Hake S. The bearded-ear encodes a MADS box transcription factor critical for maize floral development. Plant Cell. 2009;21:2578-2590. DOI 10.1105/tpc.109. 067751.

20. Weigel D., Alvarez J., Smyth D.R., Yanofsky M.F., Meyerowitz E.M. LEAFY controls floral meristem identity in Arabidopsis. Cell. 1992; 69:843-859. DOI 10.1016/0092-8674(92)90295-N.