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ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #303218
Title: Determining nitrate and ammonium requirements for optimal in vitro response of diverse pear species

Author
item WADA, SUGAE - Oregon State University
item Niedz, Randall
item Reed, Barbara

Submitted to: In Vitro Cellular and Developmental Biology - Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2015
Publication Date: 1/23/2015
Citation: Wada, S., Niedz, R.P., Reed, B.M. 2015. Determining nitrate and ammonium requirements for optimal in vitro response of diverse pear species. In Vitro Cellular and Developmental Biology - Plants. 51(1):19-27.

Interpretive Summary: There are two major nitrogen components involved in nitrogen (N) nutrition of typical tissue culture growth media, and the total amounts and ratios influence shoot formation. This study was designed to determine the optimal N requirements in pear shoot culture medium. Five pears representing four species from the pear germplasm collection of the US Department of Agriculture, National Clonal Germplasm Repository-Corvallis (NCGR) were evaluated. Cultures were evaluated for overall quality, shoot length, multiplication, leaf characteristics and callus production. Significant improvement was observed in overall shoot quality, multiplication and length for all five genotypes with changes in N nutrition. Reduced callus was seen in four genotypes and greener leaves and a reduction or elimination of leaf spots/necrosis was seen with three. Each species had a distinct response and the N form could be altered to produce longer shoots, more shoots or decreased callus formation. This study indicates that optimizing the N components of a growth medium is very important when working with diverse plant germplasm.

Technical Abstract: Inorganic nitrate (NO3-) and ammonium (NH4+) are the two major components in nitrogen (N) nutrition of typical tissue culture growth media, and the total amounts and ratios influence both shoot induction and differentiation. This study was designed to determine the optimal N requirements and NH4+ to NO3- ratios in a partially optimized pear shoot culture medium. P. communis cultivars ‘Horner 51’ and ‘OH×F87’, P. cordata, P. pyrifolia ‘Sion Szu Mi’, and P. ussuriensis ‘Hang Pa Li’ from the pear germplasm collection of the US Department of Agriculture, National Clonal Germplasm Repository-Corvallis (NCGR) were evaluated. Response surface design was used to create and analyze treatment combinations of NH4+, K, and NO3-. Cultures were evaluated for overall quality, shoot length, multiplication, leaf color and size, leaf spotting and necrosis, and callus. Significant improvement was observed in overall shoot quality, multiplication and length for all five genotypes. Reduced callus was seen in four genotypes and greener leaves and a reduction or elimination of leaf spots/necrosis was seen with three. Each species had a distinct response and the N form could be altered to produce longer shoots, more shoots or decreased callus formation. For the best quality shoots, P. communis cultivars required high NO3 and low to moderate NH4+; P. cordata quality was best with high NO3- and NH4+; P. pyrifolia ‘Sion Szu Mi’ quality improved with moderate NO3-; and high NH4+. P. ussuriensis ‘Hang Pa Li’ required low NO3- and NH4+. This study indicates that optimizing the N components of a growth medium is very important when working with diverse plant germplasm.