title: Evaluation of different pulverisation methods for RNA extraction in squash fruit: lyophilisation, cryogenic mill and mortar grinding.
abstract: BACKGROUND
  Quality and integrity of RNA are critical for transcription studies in plant molecular biology. In squash fruit and other high water content crops, the grinding of tissue with mortar and pestle in liquid nitrogen fails to produce a homogeneous and fine powered sample desirable to ensure a good penetration of the extraction reagent.
  
  
  OBJECTIVE
  To develop an improved pulverisation method to facilitate the homogenisation process of squash fruit tissue prior to RNA extraction without reducing quality and yield of the extracted RNA.
  
  
  METHODS
  Three methods of pulverisation, each followed by the same extraction protocol, were compared. The first approach consisted of the lyophilisation of the sample in order to remove the excess of water before grinding, the second one used a cryogenic mill and the control one a mortar grinding of frozen tissue. The quality of the isolated RNA was tested by carrying out a quantitative real time downstream amplification.
  
  
  RESULTS
  In the three situations considered, mean values for A(260) /A(280) indicated minimal interference by proteins and RNA quality indicator (RQI) values were considered appropriate for quantitative real-time polymerase chain reaction (qRT-PCR) amplification. Successful qRT-PCR amplifications were obtained with cDNA isolated with the three protocols.
  
  
  CONCLUSIONS
  Both apparatus can improve and facilitate the grinding step in the RNA extraction process in zucchini, resulting in isolated RNA of high quality and integrity as revealed by qRT-PCR downstream application. This is apparently the first time that a cryogenic mill has been used to prepare fruit samples for RNA extraction, thereby improving the sampling strategy because the fine powder obtained represents a homogeneous mix of the organ tissue.
authors.affiliation: IFAPA-Centro Alameda del Obispo., Área de Mejora y Biotecnología, Avda. Menéndez Pidal s/n, Apdo. 3092, 14080, Córdoba, Spain. mariab.roman@juntadeandalucia.es
authors.forename: Belén
authors.initials: B
authors.lastname: Román
authors.forename: Clara I
authors.initials: CI
authors.lastname: González-Verdejo
authors.forename: Francisco
authors.initials: F
authors.lastname: Peña
authors.forename: Salvador
authors.initials: S
authors.lastname: Nadal
authors.forename: Pedro
authors.initials: P
authors.lastname: Gómez
mesh_terms: D001671:Biochemistry / Q000295:instrumentation / Q000379:methods*; D028464:Cucurbita / Q000235:genetics*; D018076:DNA, Complementary; D005612:Freeze Drying; D005638:Fruit / Q000737:chemistry / Q000235:genetics*; D018749:RNA, Plant / Q000302:isolation & purification*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D018076:DNA, Complementary; D018749:RNA, Plant